Routine HIV screening among blood donors in Buenos Aires (Argentina): Results from six years' experience and report of a single window-period donation

ABSTRACT

Antecedentes. En Argentina, la detección de anticuerpos anti-VIH (virus de la inmunodeficiencia humana) es obligatorio desde 1991 y desde 1997 se recomienda el tamizaje del antígeno p24. MÉTODOS. Se tamizaron un total de 30.132 donaciones sucesivas. A las muestras repetidamente reactivas se les realizó otra reacción de tamizaje y/o Western blot (WB), para anticuerpos anti-VIH, o ensayo de neutralización para el antígeno p24. RESULTADOS. Se obtuvieron el 0,3623% de muestras repetidamente reactivas y el 0,2084% de donantes verdaderamente infectados con VIH. Sólo un donante resultó no reactivo para anti-VIH, repetidamente reactivo para antígeno p24 y positivo por neutralización con posterior seroconversión. Las muestras con razón (..) (AU)

ABSTRACT

Background. Blood donor HIV antibody detection has been mandatory in Argentina since 1991, and p24 antigen screening was recommended in 1997. Methods. A total of 30,132 consecutive donations were screened. Repeatedly reactive samples were tested by another screening test and/or by Western blot (WB) for HIV Ab, or by a neutralization assay for p24 Ag. Results. Among the total, 0.3623% of samples were repeatedly reactive and 0.2084% were true HIV-infected donors. Only one donor tested nonreactive for HIV Ab, repeatedly reactive for p24 Ag, positive by neutralization assay, and seroconverted later. Samples with a signal-to-cutoff (S/CO) ratio ¡Ý 3.00 on routine HIV Ab testing were 100.0% positive by WB and/or repeatedly reactive by the second test. In samples with a S/CO ratio < 3.00, 11.1% were positive by WB and/or the majority were nonreactive by the second test. Among HIV-infected donors, 89.5% possessed risk factors (which had been denied previously), 56.5% were repeatedly reactive by other screening procedures and 88.6% were coinfected with other blood-transmissible viruses. Conclusions. When the EIA S/CO ratio is ¡Ý 3.00, WB can be replaced by a second screening test. The pre-donation questionnaire should be improved to detect risk behavior in prospective donors. There was a high association between HIV and other blood-transmissible viruses (AU)